Method of making an element having a fin



Feb. 10, 1953 s. M. SCHWELLER 2,627,652

METHOD OF MAKING AN ELEMENT HAVING A FIN Filed Sept. 29. 1949 2SHEETS-SHEET l IN V EN TOR. SYL vrsnw 1 J'cmveu. m.

lf/J A TTUE/YEYS Feb. 10, 1953 s. M. SCHWELLER 2,627,652

METHOD OF MAKING AN ELEMENT HAVING A FIN Filed Sept. 29. 1949 2SHEETS-SHEET 2 I l I I 1 INVENTOR. in vayrel-Srnwa; Ex.

Ill LL 1/1: A TTakNEYS Patented Feb. 10, 1953 I METHOD OF MAKING ANELEMENT HAVING A FIN Sylvester M. Schweller, Dayton, Ohio, assignor to IGeneral Motors Corporation, Dayton, Ohio, a corporation of DelawareApplication September 29, 1949, Serial N 118,487

1 Claim.

This invention relates to refrigeration and particularly to heatexchangers employed in refrigerating systems.

An object of my invention is to provide an im- Fig. 10 is an enlargedview of a thin disc-like portion removed from the metal piece inaccordance with the present method; and

Fig. 11 is a sectional view of the disc-like porproved and lower cost.heat transfer device or tion shown in Fig. 10. heat exchanger. Referringto the drawings, for illustrating my Anot r Obj c of my invention is toprov a invention, 1. have shown in Fig. 1 thereof a rec- W cost finelement adapted to be mounted on a tangular or square-shaped piece [5 ofaluminum fluid conduit of a heat exchan r a an which may be cut fromsheets or ribbon-like rolls proved method of fabricating the fin. ofthin aluminum. The piece [5 may be substan- A still further object of yinvention is to P tially pure aluminum known to the trade as Comd aimproved method o making a fi mercial Aluminum and consisting of 2%copperj ment-from thin sheet metal stock and to provide 1,()% iron andsilicon; .05% manganese; .10% the fin element W th a c a pertion adaptedto zinc; .05% each of the alloys and the remainder embrace a conduit ofa heat exchan r. pure aluminum. This metal in addition to'being A morespecific object of my in n n is to of' high heat conductivitmsuitablefor use in fabricate a fin element from a substantially heat transferdevices and of low cost, is also qua piece o ma l a le sh t m al bycausin readily malleable and suitable to be worked or the metal to fiowand forma thin circular-shaped deformed under pressure. The metal piecel5 fin portion and an integral central collar portion (see Fig. 2) isapproximately 3 2" in thickness. extending outwardly beyond each sidethereof to A fin element 16 produced by deforming piece provide meansfor spacing the fins of the elements 15 in the manner or by the methodhereinafter from one another on a conduit of a heat e described is shownin Figs. 3 and 4, and includes changer. a circular fin portion [1,having a central hole [8 Further objects an advantages f he presenttherein bounded by a collar H) which projects invention will be apparentfrom e following (1 outwardly from each side of the fin portion ll. s preference b n ad t th a mpa y- The fin portion 11 of element I6 ispreferably, ing drawings, wherein a preferred form of the although notnecessarily, tapered by being thicker present invention is clearlyshown. adjacent collar l9 than at its outer edge. A plu- In thedrawings: rality of the fin elements l6 are strung or mount- Fig. l is aview of a square piece of sheet metal ed on a conduit 2| (see Fig. 5) ofa heat transto be formed into fin element in accordance with for device,or heat exchanger such, for example, my method; as a condenser orevaporator employed in re- Fig. 2 is an end view of the metal pieceshown frigerating and the like systems. Fin elements in Fig. 1; It maybe secured'in intimate thermal contact Fig. 3 is a side View of a finelement made in with the wall of conduit 2|, for increasing theaccordance with my present method; heat transfer surface thereof, in anysuitable or Fig. 4 is a sectional view of the fin element conventionalmanner. The fin portion ll of eleshown in Fig. 3; ment l6 extendsoutwardly from the collar IS in- Fig. 5 is a side view partly in sectionof afinned 4o termediate its ends and the collar I9 is of utconduit ofaheat exchanger; most importance since it provides a large area Fig. 6is a vertical sectional view of a two-part to pick up heat from the wallof condenser condie employed in the present method, showing the duit 2!and also serves tospace the fin portions metal piece disposed in acavity of one part of I! of elements Hi from one another. The spacingthe die; collar l9 furthermore eliminates the use of ex- Fig. 7 is afragmentary view of a part of the die pensive rack or rack-like tools ordies, for spacing taken on the line 1-1 of Fig. 6; fin elements on aconduit prior to or at th time Fig. 8 is an enlarged fragmentaryvertical secfin elements are bonded 0r secured thereto. tional view ofthe die showing the metal of the I have illustrated only the die partsemployed metal piece flowing into a confined space within to carry outthe method of fabricating fin elethe die; ments as hereinafterdescribed, since the con- Fig. 9 is an enlarged fragmentary verticalsec' struction and Operation of punch or pressing tional view of the dieshowing the metal of the machines litilizedito move the die partsrelative metal piece flown into the desired shape to form to one anotherare conventional and well known. a fin element of the present disclosureIn Fig. 6 of the drawings I show a die comprising an upper part and alower part generally represented by the arrows and reference characters25 and 26 respectively. These parts are secured to relatively movablemembers 27 and 28 respectively of a punch or pressing machine. The punchor press moves the upper member 2? downwardly so as to bring the dieparts 25 and 26 into cooperative relation with one another. Upper diemember 25 comprises a plate 3| rigidly mounted upon the upper member 21and a plurality of screws 32 in plate 3! are threaded into another plateor die element 33 carried by and movable relative to plate 3!. A spring36 surrounds each screw 32 for a purpose to be hereinafter described.The mounting of plate 3| to member 27 looks an element comprising a head35 and a plunger 37 thereto. The plunger 31 extends through plate 3!into a hole provided in plate 33 and is adapted to project beyond theplate 33 when this plate is moved a predetermined distance relative toplate St. A plurality of dowel pins or the like 38 may be employed inaddition to the screws 32 for guiding the movement oi plate 33 relativeto plate St. The lower face 39 of plate 33 is provided with a cut-outportion or groove ll and has a circular boss d2 projecting therefrom fora purpose to be hereinafter described. The hole in plate 33 in whichplunger 3? moves is provided at its lower end with an enlarged portionor counterbore 43 to be presently described.

Lower die part 25 comprises a base 4%, secured to member 23 and having alarge hole l; there in, a plate 49 resting on top of base 46 and anotherplate 51 supported upon plate 49. Both plates '39 and 53 and base d6 arerigidly secured to one another and to member 28 by suitable bolts andscrews (not shown) which pass through the plates and base and arethreaded or an chored in the member 28. Top plate M of die part 25 isbored out as at 56 and intermediate plate 453 is bored out as at 51 forthe reception of a shouldered movable element 58. A plurality of springs59, located in counterbores 68 provided in plate d9, normally hold themovable element 58 in its upper position as shown in Fig. 6 of thedrawings, with its top surface spaced below the top surface 62 of dieplate '6 so as to provide a circular cavity El in the face surface ofthis die plate for a purpose to be presently described. The element 58is provided with a hole, centrally thereof, corresponding to and alignedwith a central hole provided intermediate plate 49, for the reception ofa plunger 63 of a shaft member 64 which'is movable relative to plates 49and El and base 46 of die part 26. Shaft member '64 'has' an enlargedshouldered portion 66 thereon which moves along and is guided by thewall surface of hole 41. A strong spring 8'1 is interposed between theshouldered portion 68 of shaft Stand the face of member 28 to normallyforce shaft 64, its shouldered portion 66 and its plunger portion 63upwardly into the position shown in Fig. 6 of the drawings. The upperend of the hole in element 53 is provided with an enlarged portion or'counterbore 69 so as to match or correspond to the counterbore 43 inthe plunger holof lower plate 33 in the die part 25. "A'tube Tl fits ina groove 32 provided in the face- 62 of plate 5! of lower die part 26and is rigidly held in place on diev part 26 by a metal strap 13 andscrews M (see- Fig. 7). One end of the tube "H terminates adjacent thewall of cavity El in die'part 2'6 and its other end is connected to asource" of supply of air under pressure for a purpose to be hereinafterdescribed. The elements of die parts 25 and 26 are normally held in theposition shown in Fig. 6 of the drawings with the faces 39 and 62respectively thereof spaced from one another a suitable distance topermit access by the operator of the punch press to the die cavity 6!.

Operation of the apparatus, to carry out the method of making finelements of the prescribed shape as herein disclosed, will now bedescribed. The operator places one of the square metal pieces in thecircular cavity iii of die part 2t so that the same rests on and issupported by movable element 58 (see Figs. 6 and 7). The operator thentrips the press to cause the same to move upper die part downwardlytoward the lower stationary part 25 of the die. For a betterunderstanding of the operation of the device it is desired to point outthat the force exerted by spring 6? is much greater than the combinedforce exerted by springs 34 and 59 and that the force exerted by springsis greater than the force exerted by springs 55. Movement of die part 25downwardly into cooperative relation with die part 26 moves the face ofboss 32 into the cavity 61 in die part 25 and. into engagement with themetal piece 55 to thus clamp the piece 5?. within a confined space inthe die bounded by boss t2, movable element 53 and plate 5:. Furtherdownward movement of the die part will cause boss 42. t move element 53,with metal piece it, therebetween, downwardly to compress springswhereupon the upper end of round plunger portion 63 of shaft will engagea cylindrical center portion of the underside of metal piece i5.Continued downward movement of die part 25 will compress springs 3-5 andpermit relative movement between the plates. 31 and 33 whereupon thelower end of plunger 3.! will move into alignment with the face or boss42 and thereby engage a cylindrical center portion of the upper side ofmetal piece l5 corresponding to the central portion thereof engaged byplunger 53. It being understood that the face 32 of plate and face 62 ofplate 5! arestill spaced 9. substantial distance from one another, afterthe above described movements have taken place, so as to permitadditional downward movement of die part 25 relative to die part 2 5.Therefore additional downward movement of die part 25 causes plungers 31and 63 to apply force to the cylindrical center portion of metal pieceto flow the. metal thereof later-ally or outwardly away from the centralportion of piece it: into those portions of the confined space in thedie bounded by the face walls of boss 42, movable element 58, walls ofbore 56 and walls of the counterbores 43 and 59 as shown in Fig. 8 ofthe drawings. t will benoted by reference to the enlarged View Fig. 8,that the ends of plungers 3? and 63 are slightly rounded and that thepressure exerted, upon the piece 15 thereby causes substantiallyallofthe metal t flow outwardly away from the plungers but for a thindisc-like portion Ti which in actual practice of the invention isapproximately .008" in thickness at its outer. edge. It should also benoted that the face as of plate 33 on die part, 25 and the face 52 ofplate 5| on die part 26 are still spaced from one another during theapplication of pressure, by the. plungers, to the central portion ofmetal piece 5 to cause the metal thereof to flow so as to permit furtheradditional downward movement of die part 25 and consequently plunger 31relative to die part 26. Thus further additional downward movement ofdie part 25, beyond that illustrated in Fig. 8, will cause plunger 31and consequently plunger 63 to move down relative to other elements ofthe die and sever the disc-like part 11 from the piece 15 while at thesame time applying pressure to the metal flowing from between the endsof plungers 31 and 63 to spread and fill the confined space between boss42 and element 53 as shown in Fig. 9 of the drawings. The application ofpressure to the metal flowing outwardly from the central portion of thepiece l5 changes its form from a square shape to a circular shape. Thefurther additional movement employed to fashion the piece 15 into thefinal shape thereof desired causes the shaft 64 in die part 25 to moveagainst the force of spring 61 which spring therefore serves to cushionthe final movement of the device. It is to be understood that in movingthe face 39 of die part 25 into abutting relation with the face 62 ofdie part 23 the groove M in the face surface 39 serves to receiveconduit 1| without damaging the same.

In Figs. 10 and 11 I have shown enlarged views of the small thindisc-like portion 11 which is severed from piece I5 and which representsall the waste metal involved in the present method of making the finelement 16. As before stated in actual practice the disc-like portion 11is only approximately .008" thick at its edge and so thin in the centerthat the thickness thereof is incapable of being measured. In fact theflow of metal away from the central portion of piece 15 is frequently sorapid under the pressure applied thereto that a hole is formed in thedisc 11.

After the fin element [6 has been formed by the method described thetwo-part die and elements thereof are returned to their normal positionshown in Fig. 6. The member 21 is elevated to move die part 25 upwardlyrelative to die part 26 thereby withdrawing boss 42 from the cavity 6|and withdrawing plunger 31 from the collar portion IQ of fin element ISin die part 26. This permits spring 61 to return plunger 63 to itsnormal position and springs 59 to move element 58 upwardly to its normalposition. During the return of these elements to their normal positionillustrated in Fig. 6 of the drawings, air under pressure is conductedthrough 6 the tube 11 and directed into the cavity 6| of die part 26 andthis air forces the fin element 16 and disc-like portion 11 out of thedie.

From the foregoing it should be apparent that I have provided a novelmethod of making a. fin element with a minimum of waste. By my methodthe fin element may be fabricated from sheet or ribbon metal which is oflow cost and provides a heat exchanger of high efficiency.

While the form of embodiment of the invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, as may come within the scope of the claim whichfollows.

What is claimed is as follows:

The method of making an element having a fin portion with a central holetherein bounded by a collar projecting from both sides of the finportion which consists in, placing a malleable piece of metal in acavity in one part of a single die set adapted to have parts thereofmoved into cooperative relation with one another to provide a confinedspace of appropriate configuration for fashioning the piece into theshape desired, moving one part of the die set toward the other partthereof to cause portions of the die set to engage and apply pressure toa center portion of the piece to flow all the metal of the piece but athin part outwardly away from said center portion into other portions ofthe confined space, continuing movement of parts of the same single dieset further toward one another to cause portions of the die set to severthe thin part from the piece, and simultaneously therewith causing partsof the die set to apply additional pressure to the flowing metal tospread and fill the confined space in the die set.

SYLVESTER M. SCHWELLER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,599,572 Lusher Sept. 14, 19261,971,083 Schlaa Aug. 21, 1934 2,227,440 Church Jan. 7, 1941 2,328,098Remington et a1. Aug. 31, 1943 2,348,875 Beard May 16, 1944 2,413,591Sturdy Dec. 31, 1946

